Duplex Metering Pump Having a Single Liquid End

ABSTRACT

An improved motor driven duplex metering pump comprising two diaphragms in a single duplex liquid end pump housing assembly. The single duplex liquid end is rigidly attached to a main pump housing at a single mounting position and includes integrated check valves to allow for a single discharge process connection and a single suction process connection. The pump utilizes an improved cam mechanism that creates continuous positive uniform reciprocating motion. That continuous positive uniform reciprocating motion is imparted from its cam mechanism and its follower assembly to drive shafts that are connected to a cross arm and in collectively they impart the same motion to its two diaphragms that reciprocate 180° out of phase from each other. The result is substantially continuous liquid flow rate delivery by the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/198,754, filed Jul. 30, 2015, and U.S. Provisional Application No.62/183,202, filed on Jun. 23, 2015 the entirety of each is incorporatedherein by reference.

FIELD OF THE INVENTION

This application relates to motor driven metering pumps, andspecifically to an improved motor driven duplex liquid end meteringpump.

BACKGROUND OF THE INVENTION

Motor driven chemical metering pumps or proportional pumps are commonlyutilized to pump various liquids. They have the ability to vary theirvolumetric liquid displacement during their normal operation. This istypically achieved with their ability to change their discharge strokelength and or motor speed to vary the strokes per minute during theiroperation. This changes their liquid volumetric displacement. There arecommercially available pumps that change their flow delivery by changingtheir motor speed or stroke length only.

These motors typically have one or more displacers commonly of aplunger, diaphragm or tube design. Two displacer pumps are commonlytermed as duplex metering pumps. Duplex metering pumps would typicallyhave each of the two separate displacers held in its separate liquid endpump housings. A side view of a duplex metering pump would show the pumphousings parallel aligned side to side, either horizontally orvertically. Each pump housing has its own pump gear box or transmissionshousing or main pump housing that are rigidly connected side to side.Both would typically have four liquid process connections. That is onedischarge and one suction on each separate liquid end pump housing.

Conventional duplex pump metering pumps typically have four check valveassemblies. These valves are external, but rigidly connected to eachliquid end. This prior art design has the pumped liquid flowing throughall four valves. This requires more complex piping to integrate the twosuction and two discharge check valves.

It therefore, would be desirable to construct a duplex motor drivenduplex metering pump having a compact design of a simplex pumpconfiguration having one liquid end with one diaphragm that is mountedat one position to the main pump housing. It would be advantageous tointegrate the check valves into a single duplex liquid end as opposed tobeing external to the liquid ends. This would allow for a duplexmetering pump to be connected to a process with a single pipe connectionat the suction and the discharge sides of the pump. These processconnections would be incorporated into the body of the single duplexliquid end.

This allows the liquid pumped through the pump to flow through housingand not through the check valves. This is advantageous, because thevalves can be smaller in size for a given flow capacity of the duplexmetering pump. This is due to the check valve body does not have to belarge enough to have liquid flow around the valve's internal geometry.

Typically these duplex motor driven metering pumps will have atransmission housing or a pump housing. Within the housing there will besome form of one or two eccentric members, such as a cam or other formof mechanics. These mechanics convert rotary motion to rectilinearreciprocating motion. Typically there is a gear set within the pump'stransmission for motor speed reduction and torque multiplication. Gearsrequire some form of lubrication and the state of art metering pumps usegear oil or grease, depending on its design. The pumps will have variousshafts that are reciprocating and rotating and where they protrudethrough the transmission housing, wiping seals are used to contain thelubricant. It would desirable to have a metering pump that does notutilize gearing. Gears within the pump housing add expenses to thepump's manufacturing costs. During the normal operation of the prior artmotor driven pumps with gearing, the required gear lubricant will beneed to be changed. In addition to contain the lubricant in the pumphousing for the current state of art metering pumps over time the sealsaround the pump's shafts need to be replaced.

It would be desirable to design a metering pump that does not require alubricant or wiping seals. It would be desirable to have allreciprocating and rotating shafts within a pump design that aresupported and aligned with self-lubricated bearings that do requireexternal lubrication.

This class of pumps utilize current state of art motors includingdigital type of motors. They typically are so designed to utilize motorcontrol technology that allows for the drive motor to vary its speed tochange the pump's momentary liquid flow creation. There are manufactureswith a commercially available pumps that utilizes a digitally drivensynchronous motors. For example, U.S. Pat. No. 6,948,914 and U.S. Pat.No. 7,118,347 disclose a digital impulse control logic. This digitalimpulse controls the velocity of the pump's single diaphragm to create adesired liquid delivery velocity. Its digital control electronicsutilizes an impulse modulation that turns its motor on and off forprescribed time intervals. It would be desirable to have a metering pumpthat utilizes a digital motor, but only requires standard availablestate of art speed control to operate for speed modulation.

There are various patents that utilize a stepper motor or motors. Forexample, U.S. Pat. No. 6,293,756 is a pump system with four plungersthat is designed for the needs of High Performance Liquid Chromatography(HPLC) applications. The concept is to control a desired flow rate basedon an input of a pressure variable to the pump's controller. The basicdesign concept is four independent plunger pumps driven by fourindependent stepper motors. In the patent description it describes eachmotor driving a wheel cam via a 4:1 gear reducer set. The liquid flow ofeach independent pump is combined to create a single liquid continuousflow rate. The controller independently controls each motor speed to getthe desired combined liquid flow rate relative to pressure.

It would be advantageous to divide the work of the pump's momentaryliquid displacement and replenish over multiple synchronized steppermotors or other types of synchronous motors. These motors are eitherconnected to the pump's eccentric member via gearing or directly coupledwithout gearing depending on the design. The momentary liquiddisplacement is equally divided to two motors driving one displacer thatis pumping the liquid at any given moment in the pump's operation. Thisis opposed to U.S. Pat. No. 6,293,756 that has a stepper motor connectedto each of its single displacer, described as plungers.

Metering pumps of this class typically have defined batch flow ratedelivery. Each displacer displaces a given batch volume of liquid foreach of its displacement cycles. The current state of art metering pumpstypically have the liquid being pumped going from zero velocity at thebeginning of a batch to peak velocity and back to zero at the end of thebatch. This causes negative pulsating pressures being acted upon by thepump's liquid flow rates. These pressure variations are transferred tothe liquid up-stream and down-stream of the liquid end of the pump.These sudden changes in liquid velocity creates mass accelerationproblems being transferred to the pumped liquid. This causes undesirablepressure variations that in turn creates what is commonly called waterhammer or cavitation. This is due to the sudden stopping of the liquidon the suction and discharge side of the pump at an end of a batchcycle. This causes wide pressure variations to be established, includingnegative pressures at the suction and discharge sides of the pump.

These pumps requires check valves to operate. These check valves requiresufficient substantially continuous differential pressure across them tooperate properly. Widely varying differential pressure at the checkvalves cause its ball or other geometry in the check valves to notproperly seat. That is that the sealing geometry can float or bounce ifthe proper differential pressure is not maintained across the pump'scheck valves. It would be advantageous to design a duplex metering pumpthat better sustains a more constant differential pressure across itscheck valves for better pump performance.

These wide pressure variations, as described above are typicallymitigated by the installation of a back pressure valve on the dischargeside of the pump. It helps assure that there is sufficient back pressurefor the check valve on the pump to properly seat. It further mitigatesthe magnitude of the pressure variations on the discharge side of thepump. It does not always solve the problem. It would be desirable tohave a duplex metering pump that mitigates this pulsating flow rate andwide pressure variations being imposed on the pumped liquid. That is thebatch flow delivery remains, but the time between batches issufficiently small to mitigate the wider pressure variations beingcreated by a duplex metering pump.

In addition, when the liquid displacement velocity of one batch ends,the liquid velocity of the next beginning is substantially the same. Thevelocity of the liquid being pumped virtually never goes to zero acrossthe liquid end of the pump. It would be advantageous to have a virtuallycontinuous liquid flow across a duplex metering pump's liquid end. Theliquid that is pumped across the pump's liquid end does not go to zerovelocity which minimizes the wider pressure variations at the suctionand discharge sides of the duplex metering pump. Each liquid batchstream is commingled one after the other with virtually equal velocitiesand no dwell. It would be desirable to not require a back pressure valveto be installed on the liquid discharge side of a duplex metering pumpon many process applications.

These negative wide pressure variations and pulsating flow, as describedabove are typically also mitigated by the installation of a pulsationdampener. The dampener is installed in the discharge piping of the pump.The dampener allows the discharge piping to be quickly expandedvolumetrically during a liquid discharge event by the pump. Thepulsation dampener then reduces its volume to force the pumped liquid tothe discharge side of the pump when the pump is between a liquiddischarge events. The pulsation dampener reduces the magnitude of thepulsating flow rate delivery. It would be advantageous to design aduplex metering pump that does not typically require a pulsationdampener to create substantially low pulsating liquid flow delivery.

As described above conventional pumps require proper sustaineddifferential pressure across them to allow their check valves toproperly operate. A properly operating check valve requires a limitedtime period to adjust from opened to closed. During short time period,the suction side and the discharge liquids are comingled within theliquid in the cavity or cavities of the pump. Yet that time interval issufficiently short for pump to operate properly. When this time periodis sufficiently short, the pump will create repeatable accurate liquidflow rate creation. These check valves can have poor seating performancewhen this time interval becomes too long. This can happen when the pumpis operating at very low operational speeds.

The typical state of art metering pumps at low liquid displacementvelocities can have operating issues due to their check valves notseating properly. This is due to the time period being too long for thepump's displacers to change from at state of open to closed or closed toopen. The check valve's sealing elements will have too long of a timeperiod with the elements floating. This allows the differential pressureacross the liquid end of the pump to be equalized over the time period.This effects the accuracy and the ability of the pump to operate. Thisin practical terms reduces the achievable low end liquid displacement bymany state of art metering pumps.

It would be advantageous for the pump to have speed modulation at thelow end of its pump capacities. This would quickly increase the liquiddisplacement velocity just before and after the cross over position fora change is the reciprocating direction of the displacers. Then returnto a low displacer velocity as chosen for the application between thecross over reciprocating change in direction positions.

Metering pumps are positive displacement pumps and therefore it is ofcommon industry practice to utilize a safety relief valve (“SRV”) toprotect the pumping system from unsafe over pressurization. This SRV istypically installed inline in the discharge piping of the pumpingsystem. The valve is typically so installed to allow for the liquid tobe piped back to the suction side of the pump or back to the source ofthe liquid being pumped. That is this valve will open to allow the overpressurized pumped liquid to safely be relieved. This protects thepumping system from self-destruction. Typically this over pressurecondition happens when you have a blocked or partially blocked dischargecondition in the discharge piping. The state of art SRV is sized for themaximum liquid flow capacity for any given state of art metering pump.Typically the SRV's valve body size and capacity is determined by themanufactures recommended discharge pipe size specifications. These pipesizes are sufficiently large to minimize the liquid velocities to inturn minimize liquid mass accelerations of the pumped liquid. A drawbackof sizing the SRV based on discharge pipe size is that the SRV can getquite large and this adds costs to the overall pumping system.

As described metering pumps of this type cause liquid displacement byreciprocating a displacer and creating and collapsing a cavity orcavities. By creating a cavity, the liquid to be pumped is displacedinto the created cavity and by collapsing the cavity the liquid isdisplaced out of the pump. The process is repeated and each occurrenceis termed a stroke. A duplex pump would have two discharge and twosuction events per stroke. It is measured in strokes per minute (“SPM”).It would be advantageous to have an integral safety equalization valve(SEV) or SRV that is integrated into the single duplex liquid end.

A drawback of locating the SRV in the discharge piping is that it issized based on the pump's total capacity that is made up of the maximumsum of SPM. It would be advantageous for the SRV design capacity andphysical size being based on the liquid volume of one stroke. It wouldtherefore be advantageous to directly attach the SRV or SEV on thesingle liquid end. This would allow a much smaller SRV to accomplish thesame over pressurization protection allow for a more advantageousdischarge piping from a duplex metering pump. This is because the pumpedliquid is not piped back to the suction side of the pump or to thesource of the liquid, such as a tank.

SUMMARY OF THE INVENTION

The embodiments of the present invention address and overcome drawbacksof duplex metering pumps by providing a single duplex metering pumphaving a single liquid end with two oppositely phased diaphragms.

Embodiments of the present invention is a two motor driven duplexmetering pump. That these two motors are synchronized concurrently todrive one displacer shown as a diaphragm displacing liquid at a givenoperational moment and one diaphragm in liquid replenish. This isachieved with drive gears or direct connect type without drive gears.

Embodiments of the invention is to incorporate the eccentric cam systemfrom the invention U.S. Pat. No. 8,752,451 fixed cam assembly designwith multiple congruent non-cardioid shaped cam profiles that are sodesigned to create continuous positive motion with constant or uniformvelocity for its imparted reciprocating motion. This is virtuallysustained over the complete 360° of cam angle. That is the drive motoroperating at any given constant speed results in an advantageous virtualcontinuous uniform liquid displacement by the invention. The liquidvelocity entering the liquid end is virtually equal to the liquiddischarged from the invention. Other eccentric members of common art tocreate reciprocating motion can be utilized, but not shown or described.

Embodiments of the present invention is a design that it utilizes astepper or other type of motor or motors with direct drive. That isthere is no gear reduction utilized by the pump.

Embodiments of the invention is to have motor speed modulation controlfor diaphragm velocity management when the invention is at low liquidrate delivery. This assure that the momentary liquid velocity issufficient to quickly activate the check valve's change in state tomaintain proper differential pressure across the liquid end pumphousing.

Embodiments of the invention is to have its four check valve assembliesintegral within its single duplex liquid end or within a pump housingassembly closely rigidly connected to the duplex liquid end. Thisfacilitates the integration of two fluid streams pumped by eachindependent diaphragm or displacer to be comingled within the singleduplex liquid end. That is the liquid on the suction side of the pump iscomingled independent of the discharge side of the invention and thesame is true for the discharge side of the pump. To the discharge sideof the invention within the single duplex liquid end, the two liquidstreams for the two displacers are combined. During normal operation avirtual sustained back pressure is applied to the pumped liquid on thedischarge of the invention. This is within the internal liquid dischargechannels. That sustained back pressure would be applied to the checkvalve geometries within the check valve assemblies for efficientseating.

Embodiments of the present invention is for an integral is for overpressurization protection with an incorporated integral or close mountedsafety relief pressure equalization valve SEV or SRPEV to protect theinvention and the pumping system.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood and in order that the presentcontribution to the art may be better appreciated.

Numerous objects, features and advantages of the present invention willbe readily apparent to those of ordinary skill in the art upon a readingof the following detailed description of presently preferred, butnonetheless illustrative, embodiments of the present invention whentaken in conjunction with the accompanying drawings. The invention iscapable of other embodiments and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein are for the purpose of descriptions andshould not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

For a better understanding of the invention, its operating advantagesand the specific objects attained by its uses, reference should be hadto the accompanying drawings and descriptive matter in which there areillustrated preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate by way of example and are included toprovide further understanding of the invention for the purpose ofillustrative discussion of the embodiments of the invention. No attemptis made to show structural details of the embodiments in more detailthan is necessary for a fundamental understanding of the invention, thedescription taken with the drawings making apparent to those skilled inthe art how the several forms of the invention may be embodied inpractice. Identical reference numerals do not necessarily indicate anidentical structure. Rather, the same reference numeral may be used toindicate a similar feature of a feature with similar functionality. Inthe drawings:

FIG. 1 depicts a representative composite side view of a conventionalsimplex motor driven metering pump with one liquid end rigidly attachedat one mounting position;

FIG. 2 depicts a representative composite side view of a conventionalduplex motor driven metering pump with two opposing liquid ends acrossthe pump, each with their separate mounting positions;

FIG. 3 depicts a representative side view of a conventional motor drivenduplex metering pump with two pumps aligned side to side to each otherwith their independent liquid ends;

FIG. 3a is an end view of the liquid end for the duplex pump depicted onFIG. 3;

FIG. 4 depicts a duplex metering pump having a single liquid endconstructed in accordance with an embodiment of the present invention;

FIG. 4a is an end view of a duplex metering pump having a single liquidend constructed in accordance with an embodiment of the presentinvention, illustrating four integrated check valve assemblies;

FIG. 5 depicts an exploded view of a duplex metering pump having asingle liquid end constructed in accordance with an embodiment of thepresent invention;

FIG. 6 is a exploded top view of a duplex metering pump having a singleliquid end constructed in accordance with an embodiment of the presentinvention, illustrating drive gears between a motor shaft and a camshaft;

FIG. 7 is a side view of a duplex metering pump having a single liquidend constructed in accordance with an alternative embodiment of thepresent invention, illustrating a single duplex liquid wet end pumphousing assembly that could be substituted on the invention rather thanthe single duplex liquid end assembly;

FIG. 8 is a perspective side view of a duplex metering pump having asingle liquid end constructed in accordance with an embodiment of thepresent invention;

FIG. 8a is an elevation side view of the duplex metering pump having asingle liquid end illustrated in FIG. 8;

FIG. 8b is a cross-sectional view of the duplex metering pump having asingle liquid end taken along line D-D of FIG. 8 a;

FIG. 8c is a cross-sectional view of the duplex metering pump having asingle liquid end taken along line B-B of FIG. 8 a;

FIG. 9 is an exploded view of a duplex metering pump having a singleliquid end constructed in accordance with an embodiment of the presentinvention, illustrating a two motor construction of the duplex meteringpump with the mated motors and cam assemblies rotated 90 degrees for abetter viewing of this embodiment;

FIG. 10 is an end view of a duplex metering pump having a single liquidend constructed in accordance with an embodiment of the presentinvention;

FIG. 10a is a side elevation view of a duplex metering pump having asingle liquid end constructed in accordance with an embodiment of thepresent invention;

FIG. 10b is a cross-sectional view of the duplex metering pump having asingle liquid end taken along line F-F in FIG. 10;

FIG. 11 is a perspective view of a check valve cartridge that isconstructed in accordance with an embodiment of the present invention;

FIG. 11a is a front elevation view of the check valve cartridge assemblyof FIG. 11;

FIG. 11b is a side elevation view of the check valve cartridge assemblyof FIG. 11, illustrating a ball element inside the check valve cartridgeassembly;

FIG. 12 is an end view of a duplex metering pump having a single liquidend constructed in accordance with an embodiment of the presentinvention, illustrating an integral safety equalization valve;

FIG. 12a is a side elevation view of a duplex metering pump having asingle liquid end constructed in accordance with an embodiment of thepresent invention, illustrated without the integrated safetyequalization valve;

FIG. 12b is an enlarged view of the integrated safety equalization valveof FIG. 12;

FIG. 13 shows an end view of a duplex metering pump having a singleliquid end constructed in accordance with an embodiment of the presentinvention;

FIG. 13a is an end view of the duplex metering pump having a singleliquid end of FIG. 13;

FIG. 13b is a cross-sectional view of the duplex metering pump having asingle liquid end taken along line A-A in FIG. 13;

FIG. 14 is a graphical example to depict a given liquid volumetricdisplacement for a first diaphragm within the invention;

FIG. 14a a graphical example to depict a given liquid volumetricdisplacement for a second diaphragm within the invention;

FIG. 14b is a graphical example for the combined liquid volumetricdisplacement for a first and second displacer diaphragms;

FIG. 15 is a diagrammatic example of fluid flow characteristics for anembodiment of the invention, illustrating velocity modulation forimproved check valve seating; and

FIG. 15a is a diagrammatic example depicting velocity of an alternativemodulation for check valve seating resulting in a continuousdisplacement velocity over time and a resultant constant volumetricdisplacement over time.

DETAILED DESCRIPTION OF THE INVENTION

As a preliminary matter, it should be noted that in this document(including the claims) directional terms, such as “above”, “below”,“upper”, “lower”, etc., are used for convenience in referring to theaccompanying drawings. Additionally, it is to be understood that thevarious embodiments of the invention described herein may be utilized invarious orientations, such as inclined, inverted, horizontal, vertical,etc., without departing from the principles of the invention.

Prior art examples of a conventional simplex and duplex metering pumpdesigns are shown in FIGS. 1, 2 and 3. FIG. 1 illustrates a simplexmetering pump 28 shown in the prior art. These pumps 44 and 68 as shownin FIGS. 2 and 3 are diaphragm pumps, the diaphragms are not shown. Thecurrent art for duplex metering pumps typically have each of the twoindependent liquid ends 36 or 56 with two separate rigidly matedmechanical flanged support positions 12 or 36 as shown on FIGS. 2 and 3respectively. The mounting supports flange positions 38 or 60 areincorporated into the transmission housing, also known as the main pumphousing 40 or 66 for rigid support as shown on FIGS. 2 and 3respectively. Pump 44 depicts a conventional design that has itsmounting flanges 38 opposing to either side of transmission 40, eachsupporting a liquid end 36 at a separate mounting flange positions 38.The prior art version as shown on FIG. 3 pump 68 has two support flanges60 each mated to a liquid pump end 56.

FIG. 1 is a representative side view of a conventional motor drivensimplex metering pump 8. Metering pump 28 has a single liquid end pumphousing 10 that is rigidly held to the transmission gear box housing 14at liquid end mounting flange 12 by bolts 18. This mounting flangeposition 12 is typically rigidly incorporated into the transmission gearbox housing 14. They typically will have two external single check valvehousings 20. The motor mount flange 16 is incorporated into the gear boxhousing 14 with an attached motor 26. It would typically have a set ofdrive gears, an eccentric member and other components not shown, toreciprocate its displacer within its liquid end 10. It can have a strokelength adjustment knob 22 that changes the stroke length and its liquidflow rate change or a motor driven stroke adjustor, not shown. There arecommercially available simplex metering pumps that do not have strokeadjustment and will not have a knob 22 and utilize speed modulation onlyby its drive motor to vary the volumetric liquid displacement of thepump.

FIG. 2 is representative side view for a conventional motor drivenduplex metering pump 44 with two opposing liquid ends 36 across the gearbox or pump housing 40. The pump 44 has two liquid end pump housings 36rigidly held to their mating pump mounting flanges 38 by bolts 34 to thepump housing 40. Each of the liquid end pump housings 36 has its pair ofexternal check valve assemblies 32, one suction and one discharge. Thisconventional duplex metering pump has four process connections at eachof the four check valves 32, including two suction and two dischargeconnections. The motor mount flange 46 and motor 48 are rigidlyconnected to gear box 40. The motor 48 would typically drive theinternal eccentric or eccentrics within the pump housing 40 that in turncause the reciprocating motion of the pump's two displacer diaphragms,not shown. Each liquid end pump head 36 would have a single diaphragm,not shown.

FIGS. 3 and 3 a are a representative views for another design of aconventional duplex metering pump 68. This duplex metering pump 68 is arepresentative inline side-to-side pump design having at least twoliquid ends 56. It would typically have one gear housing 66 per liquidend 56. As is consistent with other duplex metering pump designs, pump68 has a liquid end pump housing 56 connected at pump mounting flanges60 with attachment bolts 62. The pump 68 has its common motor 52,mounted to flange 54 and a single stroke adjustor knob 70 for eachdisplacer. This pump design typically allows for additional pumps 68 tobe added beyond two. There is a variety of ancillary components ofcommon art not shown on these drawings to comprise a functional meteringpump. Pumps 44 and 68 depict common designs for commercially availableduplex metering pumps, but there is a wide variation of these twodesigns with similar layouts not shown.

FIG. 4 illustrates a duplex metering pump 76 having a single liquid endhousing 92 that is constructed in accordance with an embodiment of theinvention 76. FIG. 4a is an end view of the same embodiment of theinvention with a single duplex liquid end housing 92. FIGS. 4 and 4 adepict a composite configuration for one embodiment of the invention asa motor driven duplex metering pump 76 with similar viewable profile ofa simplex pump illustrated in FIG. 1. Pump 76 includes a motor 72. Inthe depicted embodiment motor 72 is described to be a stepper motor, butother variable speed motors can be utilized. Pump 76 further includes amain pump housing 78 that has a rigid liquid end mounting position 80.The single duplex liquid end housing 92 is rigidly secured at position80 with bolts 86.

This is the opposite to conventional duplex metering pumps which includetwo liquid ends 36 or 56 and two flange mounting positions 38 or 60 asshown in FIGS. 2 and 3 respectively. Thus, FIGS. 1 and 4 share a similarside profile of having only one liquid end pump housing mounted rigidlyto one mounting position 80 shown in FIG. 4 and mounting position 12 asshown in FIG. 1. The pump 76 shown in FIG. 4 includes a cover cap 90that covers the pump head bolts 86 and other ancillary components notshown.

Pump 76 utilizes four integral check valve assemblies 152, not shown inFIG. 4, but depicted in FIGS. 11, 11 a and 11 b. These valve assemblies152 are designed to be located within the duplex liquid end housing 92,as shown in FIG. 10, and allow for a single suction process connection82 and a single discharge connection 94. The liquid end housing 92includes plugs 84 to seal ports along the side of liquid end housing 92.The ports are to aid in manufacturing pump 76 and provide alternateprocess connection positions 82 and 94. The pump 76 will have anelectronic controller 74 with typical state of art speed modulation tocontrol electronic components, not illustrated in the figures. Thecontroller will allow the pump 76 to vary its liquid flow rate creationby varying speed of motor 72. FIGS. 14, 14, 14 b, 15 and 15 adiagrammatically illustrate the unique motor speed modulationcharacteristics.

FIGS. 13, 13 a, and 13 b illustrate a liquid end 208 that pump 76 canuse in place of liquid end housing 92. Pump 76 could also utilize asplit liquid end pump housings 142 a and 142 b of assembly 142 asdepicted in FIG. 7 rather than liquid end housing 92 and its components.Referring to FIGS. 10, 10 a, and 10 b, liquid end housing 92 would havea pair of diaphragms 114 a and 114 b not shown. The liquid flow ratecreation of pump 76 is depicted and graphically illustrated in FIGS. 14,14 a and 14 b.

Referring to FIG. 5, pump 76 is shown with motor 72 alternativelyextending from the side of pump 76. Pump 76 includes a base frame 98 andmounting holes 96. As depicted in FIG. 5, pump 76 is also shown in apartial exploded view to illustrate the relationship between the singleduplex liquid end pump housing 92, the transmission housing 78, and theend cap 90 to many of its components. The liquid end housing 92 isrigidly connected at mounting position 80 with bolts 86. It should beunderstood that liquid end pump housing 92 can be replaced with liquidend 208 or liquid end housing assembly 108. There is also other wet enddesigns not shown that would have similar design elements. For examplethey could be composed of multiple components to form a complete liquidend pump housing.

As depicted, pump 76 further includes a direct coupled stepper motor 72or other variable speed motor to drive the pump 76. This embodiment ofthe invention does not have a gear set within it, such as shown on FIG.6 with gear set 134. The shaft of motor 72 is directly connected to acam shaft 124 with a motor coupling 122, as best seen in FIG. 5. Themotor 72 and the cam assembly 100 could be in this orientation shown orin the vertical orientation as shown in FIGS. 4 and 4 a.

The liquid end housing 92 with plugs 84 is further detailed in FIGS. 10,10 a and 10 b. In the embodiment depicted in FIGS. 10, 10 a, and 10 b,pump 76 has valve assemblies 152 integrated into liquid end housing 92.

Referring to FIG. 5, in the depicted embodiment of the invention, thecam assembly 100 includes three congruent cams 126 on a common cam shaft124 attached to a cam follower assembly 130 that has an integrated camfollower drive cross arm 106, follower bearings 128, follower frame 132and other components not detailed. This depicted cam assembly 100 is sodesigned to cause substantially continuous uniform positivereciprocating motion. The cam system 100 has its cam follower assembly130 that has its follower bearings 128 in virtual constant contact withthe cams 126 during operation. The follower frame 132 is not fullydetailed, but depicted as a rigid assembly. An example of a suitable camis described in U.S. Pat. No. 8,752,451 incorporated herein byreference.

An alternative design is to split the follower frame 132 into two halvesthat are held together with compression or tension springs depending ondesign, however, this embodiment is not illustrated in the figures. Thesprings would be utilized to hold the split cam follower frame 132together as a complete assembly. Each of the cams 126 are congruent toeach other with non-cardioid cam profiles. The cams 126 are rigidlyconnected to cam shaft 124 and properly phased to cause in unisonvirtual continuous positive uniform reciprocating motion. There are atleast two cams 126 on a common cam shaft 124 or on multiple shafts, notshown, depending on design requirements.

The follower assembly 130 has an integral drive cross arm 106 as part ofthe cam follower frame 132 that in turn is mechanically connected to thetwo drive connecting shafts 108 a and 108 b. The drive connecting shafts108 a and 108 b project through cross arms 106 and 118 and are partiallysupported and aligned by guide linear bearings 112 that are in liquidend housing holes 174 as best seen in FIGS. 10, 12, and 13. The rods 108a and 108 b are threaded at each end and have mating nuts 104 to rigidlyconnect the shafts 108 a and 108 b to cross arms 106 and cross arm 118.The cross arm 118 is rigidly connected to a diaphragm connector shaft110 a that is connected to a first diaphragm 114 a. The cam followerdrive cross arm 106 is connected to a second diaphragm 114 b at itsconnector shaft 110 b. The first and second diaphragms 114 a and 114 bare each secured against the liquid end housing 92 by the two separatediaphragm retainer rings 116. The end cap 90 covers the outer diaphragm114 a and the other components. The liquid end housing 92 is secured tothe pump transmission housing 78 at flange mounting point 80 by bolts86. A controller 74 is not shown on FIG. 5, but would be required asshown on FIGS. 4 and 4 a.

The stepper motor 72 is controlled for speed variation by controller743. The pump 76 further includes an encoder 120 for electronic feedbackto the controller 74 for the motor 72 speed control verification. Inoperation, when the motor 72 is rotating the direct connected cam shaft124 rotates. This results in a 1:1 speed relationship between the motor72 and cam shaft 124 and its integrated cams 126. The follower bearings128 are in constant contact with cams 126. This causes a substantiallyconstant, positive velocity ratio of 1:1 and rectilinear reciprocatingmotion being imparted to the cam follower 130, its integrated drive arm106, shafts 108 a and 108 b and drive arm 118. This reciprocating motionwould have a substantially uniform velocity of motion for any givenmotor rotational speed. The drive arm 106 is directly driving diaphragm114 a and 114 b via its connecting shafts 110 a and 110 b.

Drive arm 106 drives the shafts 108 a and 108 b that are driving the arm118 and its reciprocating motion is transferred to the first diaphragmshaft 110 a and in turn to the first mated diaphragm 114 a. All of thesenamed components will operate in unison with a resultant common uniformdisplacement and replenish velocity for both diaphragms 114 a and 114 b.The 1:1 speed relationship of motor 72 through to both diaphragms 114 aand 114 b reciprocating is preserved during normal operation of theinvention. Normal operation has each diaphragm sustained 180° out ofphase. There are two cross over moments 214 as shown on FIGS. 14, 14 a,14 b, 15 and 15 a, where there is directional change of thereciprocating motion being applied to the diaphragms 114 a and 114 b.The displacers, shown as diaphragms 114 a and 114 b have equalvelocities during normal operation. These velocities can be constant orvaried to achieve desirable hydraulic flow rate characteristics, asfurther described herein.

The resultant liquid flow rate creation by this embodiment of theinvention is as shown and described by FIGS. 14, 14 a and 14 b. Thatflow rate creation can be further modified as described and shown byFIGS. 15 and 15 a. This is one design configuration of an embodiment ofthe invention, but there can be many variations of design to achieve thesame.

FIG. 6 is a top cut away view of an embodiment of the pump 76 with apartial cut away of the liquid end 92 and its common related componentsas shown in FIG. 5. The orientation of the motor 72 is different thanshown in FIG. 4, 4 a, or 5 but the functionality is not changed. Thepump 76 as depicted in FIG. 6 has a gear reduction assembly 134 for thedrive coupling of the motor 72 shaft to the cam shaft 124. All othercomponents remain the same as shown on FIG. 5 and so numericallyidentified, but not all are shown. The normal operation of pump 76 wouldbe the same as shown in FIG. 5, with the exception of the gear reduction124 between the cam system 100 and motor 72. The resultant liquid flowrate creation by this embodiment of the invention is as shown anddescribed by FIGS. 14, 14 a and 14 b. That flow rate creation can befurther modified as described and shown by FIGS. 15 and 15 a. Thesubstantially continuous uniform low pulsating liquid flow creation asdescribed in FIG. 5 of the pump 76 remains the same.

FIG. 7 is an embodiment for an alternate liquid end housing assembly 64of the invention that can be substituted for the liquid end housing 92or liquid end 208. The design of the liquid end housing assembly 64 isconsistent with liquid end housing 92 or liquid end 208 being rigidlyattached at a single mounting position 80. It and other components formthe assembly 64 that can be utilized by the pump 76 depicted in FIGS. 4,4 a, 5, 6, 8 or pump 156 depicted in FIG. 9. The assembly is rigidlymounted at position 80 of transmission housing 78, not shown.

To form a liquid end assembly 64 with two liquid ends split components142 a and 142 b that are combined to create one single duplex liquid endhousing assembly 142 as a component within the complete pump liquidhousing assembly 64. Each liquid end 142 a and 142 b could be made up ofmultiple components, not shown. Other components, such as diaphragms 114a and 114 b and their shafts 110 a and 110 b not detailed, to driveshafts 108 a and 108 b are combined with a single drive arm 144 withvarious other ancillary components, not detailed, to form the liquid endassembly 64. This complete liquid end assembly 64 with its liquid endcomponents 142 a and 142 b and its mated components are an alternatedesign to the liquid end housing 92 or liquid end 208 and their matedcomponents. This design concept is to show that the opposing diaphragms114 a and 114 b can be mounted in a different opposing back to backorientation. Each of the two diaphragms 114 a and 114 b and their driveshafts 110 a and 110 b are rigidly connected to a common drive arm 144.The liquid end housings 142 a and 142 b are held together by bolts 86and additional bolts not shown to create a complete liquid end pumphousing assembly 64. Diaphragm 114 a is attached to liquid end pumphousing 142 a and diaphragm 114 b is attached to liquid end pump housing142 b. Each diaphragm 114 a and 114 b are held to their respectiveliquid end pump housing 142 a and 142 b by a diaphragm mounting ring,not shown. This design would also have its complete liquid end pumphousing assembly 64 rigidly mounted to the pump transmission 78 withbolts 86 to its integrated mounting flange 2 position.

Drive arm 144 is rigidly attached to the two drive shafts 108 a and 108b. The drive shafts 108 a and 108 b connected to diaphragms 114 a and114 b by their shafts 108 a and 108 b. The mechanics and all thecomponents required to accomplish these rigid connections between thediaphragm's shafts 108 a and 108 b and the drive arm 144 and driveshafts 108 a and 108 b are not shown. The drive shafts 108 a and 108 band nuts 104 will be rigidly connected to the cam follower's drive arm106 as shown on FIGS. 5, 6, 8 and 9.

FIG. 7 as shown would utilize four external check valve assemblies. Thefour check valves are rigidly connected to the liquid end pump housingassembly 142. It could utilize the duplex check valve assemblies 152 asshown in FIGS. 11, 11 a, 11 b that would be incorporated into the liquidend housings 142 a and 142 b. The valves 152 would have a similarinstallation an alternate designs as detailed in FIGS. 10, 11, 11 a and11 b. The liquid end 64 would have one suction process connection 82 andone discharge process connection 94, not shown. Operationally the drivearm 144 are driven by shafts 108 a and 108 b. The operation of the camsystem 100 and follower arm 106 to shafts 108 a and 108 b to arm 144 todiaphragm shafts 110 a and 110 b to diaphragms 114 a and 114 b would bethe same as described in FIGS. 5 and 6, not shown. Operationally thediaphragms 114 a and 114 b would reciprocate the same as described forpump 76 in relation to FIG. 5, FIGS. 14, 14 a and 14 b and as modifiedas described by FIGS. 15 and 15 a.

FIG. 8 is a side perspective view of the pump 76 illustrated in FIG. 6with the liquid end 92. It shows most of the same components as shown onFIG. 6. That is head bolts 86, duplex liquid end 92, plugs 84, liquiddischarge process connection 94, but suction process connection 82 isnot shown, cam follower bearings 128, cam follower frame assembly 130,transmission gear box base frame 146 with mounting holes 96, drive crossarm 106, back of a diaphragm 114 b, diaphragm retainer ring 116, one ofthe diaphragm drive connecting shafts 108 a and 108 b, cam followerdriver cross arm 106, cam follower assembly 130, stepper motor 72 andencoder 120. Operationally it is the same as detailed for pump 76 inFIG. 5, except for the gears 124 as shown in FIG. 6.

FIG. 8c with liquid end 92 or 208 is shown with a sectional view of thecam assembly 100 on cam shaft 124 and gear set 134. The cross arm 106 isconnected to the shafts 108 a and 108 b that is connected to arm 118.The second diaphragm 114 b and its shaft 110 b are connected to arm 106and the other diaphragm 114 a and its shaft 110 a is connected to arm118. The porting channels 168 and other internal details of the singleduplex liquid end are not shown.

FIG. 9 is a partially exploded top view of an embodiment of the duplexmetering pump having a single liquid end 156 that incorporates twomotors 72. Each motor 72 has a point of connection 158 that connectsmotor coupling 122 to its independent cam shaft 124. The point ofconnection 39 could be a direct coupled drive as shown in FIG. 5 atcoupling 122 or have gear set 134 at position 158 as shown at FIGS. 6, 8and 8 c. Pump 156 has two independent cam shaft assemblies 100, eachwith its independent cam shaft 124 at its independent point ofconnection 158 with its independent mated motor 72. It also has threecongruent cams 102 on cam shaft 124 as shown for each independent camassembly 100 that are combined to compose a double cam system combinedas 154 a and 154 b. It is understood that each cam shaft includes atleast two cams, however this number could be larger depending on theapplication. The cams 126 of pump 156 operate in the same manner as cams126 of pump 76. A description of which does not bear repeating.

Each independent cam follower assembly 130 a and 130 b has its camfollower bearings 128, follower frame 132 a and 132 b and an integratedcommon follower frame drive cross arm 106. Operationally the embodimentof pump 156 with two motors 72 is basically the same as pump 76 with asingle motor as shown in FIGS. 4, 4 a, 5, 6 and 8. This is true with orwithout gears at the two positions 158. For the pump 156 as compared topump 76 with a single cam assembly 100 as shown on FIG. 5, the work ofliquid displacement being applied by the cross arms 106 is dividevirtually equally to each cam assembly 100 of cam system 154 a and 144b. Each encoder 120 gives an electrical signal feedback as to each drivemotor's momentary rotational speed and digital count position. Asdiscussed in relation to pump 14, controller 74 will use the electricalfeedbacks from each encoder 120 to automatically vary the speed of eachdrive motor 72. This is to equalize the velocity of its mated cam'sreciprocating velocity throughout the stroke motion of pump 156. Thepump 156 would compare the two motors' 72 momentary speed to determinetheir momentary velocity being imparted equal to the common connecteddrive arm 106. That is that each connection position of the cross arm106 within cam follower assembly 130 a and 139 b will have virtuallyequal rectilinear reciprocating velocity applied by each cam assembly100. This causes a virtual equalized reciprocating motion to be appliedto the drive arm 106, by each cam assembly 100. There would be certainmechanical tolerances to allow for slight miss-alignment of forces beingapplied by the two independent cam follower assemblies 130 to the crossarm 106.

It is understood that there are many ways to achieve the same equalizedand divided work of liquid displacement of pump 156 by the two camassemblies 100. Also, it is understood that the use of other forms ofmechanical, electro mechanical, or electrical feedback components may beused to keep the two drive shafts 108 a and 108 b synchronized.

All other components depicted are the same as shown on FIGS. 5, 6, and8, except where noted. In the depicted embodiment, the torque from themotors 72 is combined to increase the pump's 156 volumetricdisplacement. Operationally as each motor 72 rotates it in turn rotatesthe attached cams 126 of its cam system 100 that are mechanically summedto cam system 130 a and 130 b that imparts the reciprocating motion tothe shared cross arms 106 and then to shafts 108 a and 108 b and then toarm 106. These rigidly integrated arms 106 and 118 will drive the firstand second diaphragm shafts 110 a and 100 b and the attached diaphragms114 a and 114 b, respectively. An alternate design is of two independentseparated cam systems 100 without a common drive arm 106 could beutilized, not shown. That is each cam system 100 is independentlydriving a shaft 108 a and 108 b. The encoder's electronic feedback willallow for precise volumetric liquid displacement by controller 74 of thepump 156. With the exception of the two motors 72 and its specificdesign mechanics and electronics herein described, the operation of thepumps 156 is similar to pump 76 as described in FIGS. 5 and 6.

Operationally the resultant liquid flow rate creation by pump 43 is asshown and described by FIGS. 14, 14 a and 14 b. The flow rate creationcan be further modified as described and shown by FIGS. 15 and 15 a. Thesubstantially continuous low pulsating liquid flow displacement of theinvention remains the same.

FIGS. 10, 10 a and 10 b illustrate a liquid end housing 92 as a singlecomponent, it is understood that liquid end housing 92 could be composedof more than one component to form an assembly to achieve the same. FIG.10 is an end view of the single duplex liquid end pump housing 92. Inthe depicted embodiment, liquid end pump housing includes fourintegrated check valve assemblies or cartridges 152 that seat in area170. It has internal liquid passage ways 168 within the housing 92 thatallow the liquid to be channeled in or out of the housing 92. Thepassage ways or channels 168 on the discharge of the pump during normaloperation has a virtual sustained positive back pressure when theinvention is operating. That is the pressure wave of one displacerbeginning to displace liquid is sufficiently close with respect to timeover cam angle change to the other displacers ending its liquiddisplacement that a virtual continuous process back pressure issustained within the discharge channel 168 or general area 168 duringthe invention's normal operation. This back pressure will be reflectiveof the back pressure from the process pressure that the invention ispumping against. The pump during normal operation will mitigate thecreation of sudden low pressure issues as described above. When thepropelling displacer ends it liquid discharge displacement, the liquidtends to sustain the motion of the displacer.

To ensure there is adequate back pressure, it is common to install aback pressure valve into a pump. This mitigates cam system 20 havingvirtually zero dwell at the two moments of change in the direction ofreciprocating motion being applied to the diaphragms 114 a and 114 b.This sustained back pressure within zone in the discharge channel area168 assures that there is sufficient back pressure across the checkvalves 152 to assure proper seating on the valves when the pump isoperating under normal conditions. The cartridge check valve assembly152 would be rigidly seated in a portion of the channels 168 at areas170. The cartridge check valves 152 could be of a different design, suchas being shaped like a ball and be disposed along a seating area builtinto the liquid end housing 92, not shown. For example, a portion of thechannel 168 within the liquid end 92 could be so designed to comprise acheck valve body rather than utilizing the valve body 182 as shown onFIGS. 11 and 11 a. The invention could have other combinations ofcomponents to form an integral functioning check valve assemblies notshown.

As shown in FIG. 10, pump housing has a threaded section 82 for inlet tosuction side liquid channels 168 and the same for the discharge channels168 has a thread section discharge connection 94. Operationally theliquid flows through the inlet area 82 and into suction side areachannel 168, through the check valve 152, by entering the bottom of thecheck valve 152 and out the side and into area 170 through inlet 172,when the suction check valve 152 is open and then into the cavity areas162. When the discharge check valve 152 is open and inlet valve closesthe liquid exits the cavity 162 through outlet opening 170 through area170 through the discharge check valve 152 into the discharge channels168. The liquid would then flow out of the discharge area 94. Thishydraulic flow is caused by the motion of the diaphragms 114 a and 114 bthat collapse and expands the volumetric area of the cavities 162.Whereas the area 162 is expanded to cause a low pressure in area 162that atmospheric pressure will force liquid into this cavity area 162,due to the differential pressure acting on the liquid. Whereas thediaphragms 114 a and 114 b collapse the cavity area to force the liquidto exit the pump. This process is repeated and alternated between thecavities 162 of the liquid end 92. The appropriate check valves 152opening and closing at 180° out of phase to each other at positions 214as shown in the FIGS. 14, 14 a, 14 b, 15 and 15 a. The pump housing'stwo cavity areas 162 and their mated diaphragms 114 a and 114 b comprisethe defined two cavities of the single duplex pump housing 92.

In addition the bolt holes 166 are to allow bolts 86 to pass through tobe connect to mounting position 80 and holes 174 are for the linearbearings 112 to seat and support the drive shafts 108 a and 108 b. Area172 is the opening that connects the cavity areas 162 to channels 168.The holes 176 are the threaded holes that allow the diaphragm mountingring 116, not shown, to be rigidly attached to the liquid end housing 92to secure the diaphragms 114 a and 114 b. The areas 160 are passage waysfor alternate suction or discharge ports and would be sealed with plugs84, not shown, if not utilized for fluid porting. They also allow forthe creation of the passage way 168.

FIG. 11 illustrates a cartridge ball check valve assembly 152 that areto be integrated into the duplex liquid end housing 92, as shown in FIG.10, or into liquid end assembly 64 housings 142 a and 142 b, asdescribed in relation to FIG. 7. The check valve assembly 152 isdepicted as a ball type check valve, but the ball could be a disc, coneor other objects. There are four check valve assemblies 152, two on thesuction side and two on the discharge side of the pump. The four checkassemblies 152 would be integrated into the liquid passage ways 168 atarea 170 as shown on FIG. 10. The check valve assembly 152 includes thebody 182, a fluid passage way 178, with a ball mating seating area 184.

FIG. 12 is an embodiment of the invention shown as a side view of liquidend housing 92 with the addition of an integral safety pressure flowequalization valve assembly “SPFEV” 74, such as safety relief valve(“SRV”). As shown, the SRV is connected along the side of the singleduplex liquid end housing 92 and has channel 200 that is hydraulicallyinterconnected when the diaphragm 192 is not in a fully seated position.The channel 200 is not hydraulic connected when the diaphragm 192 isfully seated as shown. The SRV 202 includes a bonnet 188, a spring 190,the diaphragm 192 and two spring discs 206, located at either end of thespring 190, an adjustment bolt, and locking nut 194 having a cover cap204. It is understood that valve 202 may be located at differentpositions on the single duplex liquid end. The SRV 202 is used toprotect the pump and pumping system from over pressurization.

Operationally the SRV 202 changes the pressure setting by turning theadjustment bolt 194 to load the diaphragm 192 with sufficient springforce to stay on its seat during normal pump operation. If there is anunsafe pressure reached the diaphragm 192 overcome the spring 190resistance. This will allow the diaphragm 192 to lift off its seatingarea allowing pressure to equalize in the channel 200. This will causeliquid flow equalization and comingling between the two diaphragms 14 aand 114 b and protect an over pressurization condition within theinvention and the piping system. When the pump continues to operate, theliquid is shuttled between the two cavities 162 within the liquid end92, 64 or 208. When the valve 202 is open, liquid is unable to bedisplaced from the pump. When the over pressure condition is equalized,the diaphragm 192 will re-seat and the liquid within the liquid end willbe pumped. FIG. 12a is a top view of the liquid end 92 without the SRV.The SRV can be attached and integrated into all of the liquid endsincluding 92, 64 and 208 of liquid end assemblies in FIG. 5, FIG. 7, andFIGS. 13, 13 a and 13 b.

Referring now to FIGS. 13, 13 a and 13 b, the single duplex liquid endpump housing 208 is depicted without an internal check valve assembly152. It has four external check valves assemblies typical of FIG. 2check valve 32 not shown. The check valve assembly 32 would be attachedat each of the four process connections located along the exterior ofthe housing 208, not shown, and include two independent suction processconnections and two independent discharge process connections. All otherfeatures of liquid end 208 are the same as liquid end 92 as shown anddescribed with regard to FIGS. 10, 10 a and 10 b, except channel 168 isnot interconnected for each diaphragm 114 a and 114 b. Operationally theliquid end 208 would operate similar as to how liquid end 92 isdescribed in FIG. 10, except the liquid would not be comingled withinchannels 168.

FIGS. 14, 14 a and 14 b depict a diagrammatic example of the pump'sliquid volumetric flow rate displacement. That is the preferredembodiment that utilizes multiple cams 126 that are congruent geometriesas described and detailed in U.S. Pat. No. 8,752,451, the entirety ofwhich is incorporated herein by reference. These cam profiles createuniform continuous positive reciprocating motion with non-cardioid camprofiles that impart continuous uniform positive reciprocating motion tobe transferred to both diaphragms 114 a and 114 b over virtually 360° ofcam angle. This creates substantially continuous liquid displacement bythe pump over a significant range of motor speeds. That is the suctionliquid and discharge liquid velocities are substantially equal acrossthe duplex liquid end 92, 64 and 208 of the invention. Therefore thediaphragms 114 a and 114 b motion is sustained to a given directionuntil the crossover moment at position 214 and motion is reversed, whichoccurs every 180 degrees. There is virtually no or very minimal dwelltime created by the profiles of cams 126. This is accomplished withoutspring return being applied to the cam follower. FIG. 14 depicts a ratioof volumetric liquid displacement to the discharge side of the pump forone diaphragm 114 a over 180° of cam angle. V1 and V0 of FIG. 14 showthe volumetric replenishment over 180° of rotation of the cam.Specifically, V1 is the volumetric liquid to be displaced to thedischarge side of the invention by a diaphragm 114 a and V0 representsthe volumetric liquid to be replenished on the suction side of theinvention by the diaphragm 114 a.

The line 210 represents the sustained volumetric displacement as auniform velocity virtually without acceleration and 212 representsacceleration of the volumetric displacement with virtually no velocityfor the liquid to be displaced by the invention. In practical terms thisvelocity to acceleration relationship is not absolute due tocharacteristics of the pump's practical application of mechanics and thepumping system. FIG. 14a represent the same as FIG. 14 for the seconddiaphragm 114 b and its V2 volumetric displacement and V0 it's replenishby the diaphragm 11 b. Whereas V1 and V2 are 180° out of phase. Thesummed continuous liquid flow rate displacement by the pump is shown inFIG. 14b . Each displacer's volumetric displacement as depicted as V1and V2 is shown in FIG. 14b and over 360° of cam angle change. The 360°of cam angle is virtually equally divided at 180° at positions 214. Thatis that the acceleration of each volumetric displacement as shown byline 212 for V1 and V2 is substantially achieved over a very small camangle. This allows a virtually sustained high pressure within the pump'sliquid end housing 92 liquid discharge channels 168 as shown anddescribed by FIGS. 10, 10 a and 10 b. The same for liquid end 64 FIG. 7.Liquid end 208 on FIGS. 13, 13 a and 13 b that would have the samesubstantially sustained back pressure where the two liquid flow streamscombine on the discharge side of the process back to the liquid end.Within the invention there is substantially sustained back pressurewithin the discharge cavity 168 for single duplex liquid end housings 92and 64, where the liquid is comingle from the two liquid streams fromeach displacer 114 a and 114 b.

FIGS. 15 and 15 a are graphical depictions of the pump operating withlow diaphragm velocity and resultant low liquid volumetric displacement.FIGS. 15 and 15 a depict the addition of an acceleration and velocitychange being applied to the diaphragms 114 a and 114 b before and afterthe reciprocating directional cross over positions 214 every 180°.Whereas position 214 is the moment when diaphragms 114 a and 114 bchange their direction of reciprocating motion. This controlled changein acceleration and velocity increases volumetric displacement acrossthe positions 214 to assist check valve seating performance. Whereas themotor 72 or motors 72 are at very low rotational speed and thediaphragms 114 a and 114 b are at very low uniform reciprocatingvelocity and results in lower volumetric displacement 216 as compared tofull rotational speed at having a full volumetric displacement 226.

The running cam angle change over time and resultant liquid displacement216 is insufficient to properly operate the pump's check valveassemblies 152 or other external check valves. That is the free movingball or other geometry in the pump's check valve assemblies is in afloat position and will not sufficiently seat. That is there is too muchtime where the check valve will not seat properly.

To mitigate this inefficient check valve seating, the controller 74would be monitoring this low velocity condition of the pump 76 or 156 orother embodiments of the invention. The controller 74 would change themotor 72 or motors 72 speed for a sudden rise in acceleration andvelocity of the diaphragms 114 a and 114 b between points 224. Thecurves 220 illustrating the diaphragms 114 a and 114 b velocity change,as shown in FIGS. 15 and 15 a, for volumetric velocity and accelerationdisplacement have a varied time duration and peak velocities 218. Thisis dependent on the controller's 74 commands to the motor 72 or motors72. This is to cause a quick velocity change to shorten the timedifferential between positions 224. This is to assist in the properseating of the balls 180 in the check valve assemblies across position214. This is to properly assure that the differential pressure acrossthe pump is not equalized due to the extended time period when thesuction and discharge check valves 152 or external check valves wouldvirtually not be open simultaneously.

The liquid of the suction and discharge of the pump would be connectedand be of one liquid stream across the liquid end of the pump when theball or other element is floating. The sudden change in diaphragms 114 aand 114 b velocity, as shown, would increase the volumetric displacementby the invention over a shorter time period of cam angle change.Whereas, FIG. 15a adds a velocity modulation to the displacementdeceleration compensation 228, compared to displacement leading velocityof curve 220 shown in FIG. 15. To accomplish this, the controller 23will reduce the diaphragms' 114 a and 114 b velocities for the portionof the curve 228 that goes below the mean average velocity curve 216 tooffset the velocity curve 220 that is above the mean velocity curve 216.With the volumetric curve 228, the pump's net flow rate creation overthe running average displacement curve would be closer to the runningmean average liquid volumetric displacement curve of 216. That is tohave the summation of the total liquid displacement of the inventionover time be approximately constant for the running liquid flow creationover time for the displacement curve 220 at a given motor 72 speed.

A number of embodiments of the present invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A liquid end of a duplex pump, the liquid endcomprising: a body having opposite first and second sides, a first pumpcavity formed through said first side, a second pump cavity formedthrough said second side, a first suction passage formed through saidbody and in fluidic communication with said first pump cavity, a firstdischarge passage formed through said body and in fluidic communicationwith said first pump cavity, a second suction passage formed throughsaid body and in fluidic communication with said second pump cavity, asecond discharge passage formed through said body and in fluidiccommunication with said second pump cavity, a suction port formedthrough said body and in fluidic communication with said first andsecond suction passages, and a discharge port formed through said bodyand in fluidic communication with said first and second dischargepassages.
 2. The liquid end of claim 1, further comprising: a firstcheck valve disposed across said first suction passage; a second checkvalve disposed across said first discharge passage; a third check valvedisposed across said second suction passage; a fourth check valvedisposed across said second discharge passage; wherein said first andsecond check valves operate cooperatively to alternate a fluid flow in afirst direction from said suction port through said first suctionpassage and a second direction from said suction port through saidsecond suction passage; and wherein said second and forth check valvesoperate cooperatively to alternate a fluid flow in a third directionfrom said first discharge passage through said discharge port and afourth direction from said second discharge passage through saiddischarge port.
 3. The liquid end of claim 2, wherein each of saidfirst, second, third, and fourth check valves are disposed within saidbody.
 4. The liquid end of claim 1, further comprising: a firstdiaphragm disposed across said first pump cavity; a first cap attachedto said first side and closing said first pump cavity; a seconddiaphragm disposed across said second pump cavity; and a second capattached to said second side and closing said second pump cavity.
 5. Theliquid end of claim 4, further comprising: first and second connectingshaft passages formed through said body between said first and secondsides; a first connecting shaft disposed within said first connectingshaft passage for reciprocating motion therein; a second connectingshaft disposed within said second connecting shaft passage forreciprocating motion therein; a first cross arm attached to andextending between first ends of said first and second connecting shafts;a second cross arm attached to and extending between second ends of saidfirst and second connecting shafts; a first diaphragm shaft connected atone end to said first cross arm for conjoined movement therewith andconnected at a second end to said first diaphragm; and a seconddiaphragm shaft connected at one end to said second cross arm forconjoined movement therewith and connected at a second end to saidsecond diaphragm.
 6. The liquid end of claim 5, wherein: said firstdiaphragm shaft extends through said first cap and is fluidically sealedtherewith; and said second diaphragm shaft extends through said secondcap and is fluidically sealed therewith.
 7. The liquid end of claim 1,further comprising: a first check valve disposed across said firstsuction passage; a second check valve disposed across said firstdischarge passage; a third check valve disposed across said secondsuction passage; a fourth check valve disposed across said seconddischarge passage; wherein said first and second check valves operatecooperatively to alternate a fluid flow in a first direction from saidsuction port through said first suction passage and a second directionfrom said suction port through said second suction passage; wherein saidsecond and forth check valves operate cooperatively to alternate a fluidflow in a third direction from said first discharge passage through saiddischarge port and a fourth direction from said second discharge passagethrough said discharge port; a first diaphragm disposed across saidfirst pump cavity; a first cap attached to said first side and closingsaid first pump cavity; a second diaphragm disposed across said secondpump cavity; a second cap attached to said second side and closing saidsecond pump cavity; first and second connecting shaft passages formedthrough said body between said first and second sides; a firstconnecting shaft disposed within said first connecting shaft passage forreciprocating motion therein; a second connecting shaft disposed withinsaid second connecting shaft passage for reciprocating motion therein; afirst cross arm attached to and extending between first ends of saidfirst and second connecting shafts; a second cross arm attached to andextending between second ends of said first and second connectingshafts; a first diaphragm shaft connected at one end to said first crossarm for conjoined movement therewith and connected at a second end tosaid first diaphragm; and a second diaphragm shaft connected at one endto said second cross arm for conjoined movement therewith and connectedat a second end to said second diaphragm.
 8. The liquid end of claim 7,wherein each of said first, second, third, and fourth check valves aredisposed within said body.
 9. The liquid end of claim 7, wherein: saidfirst diaphragm shaft extends through said first cap and is fluidicallysealed therewith; and said second diaphragm shaft extends through saidsecond cap and is fluidically sealed therewith.
 10. A duplex pumpcomprising: a liquid end having a body, a suction port and a dischargeport through said body, a first diaphragm disposed within a first pumpcavity formed into said body, a second diaphragm disposed within asecond pump cavity formed into said body, said first and second pumpcavities being fluidically connected to said suction port and saiddischarge port; a transmission operatively connected to said first andsecond diaphragms to reciprocate said first and second diaphragms; and amotor operatively connected to said transmission and operating to drivesaid transmission.
 11. The duplex pump of claim 10, wherein said liquidend further comprises: first and second connecting shaft passages formedthrough said body between said first and second sides; a firstconnecting shaft disposed within said first connecting shaft passage forreciprocating motion therein; a second connecting shaft disposed withinsaid second connecting shaft passage for reciprocating motion therein; afirst cross arm attached to and extending between first ends of saidfirst and second connecting shafts; a second cross arm attached to andextending between second ends of said first and second connectingshafts; a first diaphragm shaft connected at one end to said first crossarm for conjoined movement therewith and connected at a second end tosaid first diaphragm; a second diaphragm shaft connected at one end tosaid second cross arm for conjoined movement therewith and connected ata second end to said second diaphragm; and wherein said transmission isoperatively connected to said first and second diaphragms by said firstand second connecting shafts.
 12. The duplex pump of claim 10, whereinsaid liquid end further comprises: a first suction passage formedthrough said body and in fluidic communication with said first pumpcavity, a first discharge passage formed through said body and influidic communication with said first pump cavity, a second suctionpassage formed through said body and in fluidic communication with saidsecond pump cavity, a second discharge passage formed through said bodyand in fluidic communication with said second pump cavity; wherein saidsuction port is in fluidic communication with said first and secondsuction passages; and wherein said discharge port is in fluidiccommunication with said first and second discharge passages.
 13. Theduplex pump of claim 12, wherein said liquid end further comprises: afirst check valve disposed across said first suction passage; a secondcheck valve disposed across said first discharge passage; a third checkvalve disposed across said second suction passage; a fourth check valvedisposed across said second discharge passage; wherein said first andsecond check valves operate cooperatively to alternate a fluid flow in afirst direction from said suction port through said first suctionpassage and a second direction from said suction port through saidsecond suction passage; and wherein said second and forth check valvesoperate cooperatively to alternate a fluid flow in a third directionfrom said first discharge passage through said discharge port and afourth direction from said second discharge passage through saiddischarge port.
 14. The duplex pump of claim 10, wherein said motor is astepper motor.
 15. A duplex pump comprising: a liquid end having a body,a suction port and a discharge port through said body, a first diaphragmdisposed within a first pump cavity formed into said body, a seconddiaphragm disposed within a second pump cavity formed into said body,said first and second pump cavities being fluidically connected to saidsuction port and said discharge port; a first transmission operativelyconnected to said first and second diaphragms to reciprocate said firstand second diaphragms; and a first motor operatively connected to saidfirst transmission and operating to drive said first transmission; asecond transmission operatively connected to said first and seconddiaphragms to reciprocate said first and second diaphragms; and a secondmotor operatively connected to second transmission and operating todrive said second transmission.
 16. The duplex pump of claim 15, whereineach of said first and second motors are stepper motors.
 17. The duplexpump of claim 15, wherein said liquid end further comprises: first andsecond connecting shaft passages formed through said body between saidfirst and second sides; a first connecting shaft disposed within saidfirst connecting shaft passage for reciprocating motion therein; asecond connecting shaft disposed within said second connecting shaftpassage for reciprocating motion therein; a first cross arm attached toand extending between first ends of said first and second connectingshafts; a second cross arm attached to and extending between second endsof said first and second connecting shafts; a first diaphragm shaftconnected at one end to said first cross arm for conjoined movementtherewith and connected at a second end to said first diaphragm; asecond diaphragm shaft connected at one end to said second cross arm forconjoined movement therewith and connected at a second end to saidsecond diaphragm; wherein said first transmission is operativelyconnected to said first and second diaphragms by said first and secondconnecting shafts; and wherein said second transmission is operativelyconnected to said first and second diaphragms by said first and secondconnecting shafts.
 18. The duplex pump of claim 15, wherein said liquidend further comprises: a first suction passage formed through said bodyand in fluidic communication with said first pump cavity, a firstdischarge passage formed through said body and in fluidic communicationwith said first pump cavity, a second suction passage formed throughsaid body and in fluidic communication with said second pump cavity, asecond discharge passage formed through said body and in fluidiccommunication with said second pump cavity; wherein said suction port isin fluidic communication with said first and second suction passages;and wherein said discharge port is in fluidic communication with saidfirst and second discharge passages.
 19. The duplex pump of claim 18,wherein said liquid end further comprises: a first check valve disposedacross said first suction passage; a second check valve disposed acrosssaid first discharge passage; a third check valve disposed across saidsecond suction passage; a fourth check valve disposed across said seconddischarge passage; wherein said first and second check valves operatecooperatively to alternate a fluid flow in a first direction from saidsuction port through said first suction passage and a second directionfrom said suction port through said second suction passage; and whereinsaid second and forth check valves operate cooperatively to alternate afluid flow in a third direction from said first discharge passagethrough said discharge port and a fourth direction from said seconddischarge passage through said discharge port.
 20. The duplex pump ofclaim 19, wherein each of said first, second, third, and fourth checkvalves are disposed within said body.